diff --git a/cbackend.cpp b/cbackend.cpp
index 2eb853e3..5fe87264 100644
--- a/cbackend.cpp
+++ b/cbackend.cpp
@@ -16,6 +16,11 @@
 #warning "The C++ backend isn't supported when building with LLVM 2.9"
 #else
 
+#include <inttypes.h>
+#ifndef PRIx64
+#define PRIx64 "llx"
+#endif
+
 #include "llvm/CallingConv.h"
 #include "llvm/Constants.h"
 #include "llvm/DerivedTypes.h"
@@ -1280,7 +1285,7 @@ void CWriter::printConstant(Constant *CPV, bool Static) {
         char Buffer[100];
 
         uint64_t ll = DoubleToBits(V);
-        sprintf(Buffer, "0x%llx", static_cast<long long>(ll));
+        sprintf(Buffer, "0x%"PRIx64, static_cast<long long>(ll));
 
         std::string Num(&Buffer[0], &Buffer[6]);
         unsigned long Val = strtoul(Num.c_str(), 0, 16);
diff --git a/expr.cpp b/expr.cpp
index 1bcfa70d..f94245d5 100644
--- a/expr.cpp
+++ b/expr.cpp
@@ -43,6 +43,13 @@
 #include "module.h"
 #include "util.h"
 #include "llvmutil.h"
+#include <inttypes.h>
+#ifndef PRId64
+#define PRId64 "lld"
+#endif
+#ifndef PRIu64
+#define PRIu64 "llu"
+#endif
 
 #include <list>
 #include <set>
@@ -4540,18 +4547,10 @@ ConstExpr::Print() const {
             printf("%f", floatVal[i]);
             break;
         case AtomicType::TYPE_INT64:
-#ifdef ISPC_IS_LINUX
-            printf("%ld", int64Val[i]);
-#else
-            printf("%lld", int64Val[i]);
-#endif
+            printf("%"PRId64, int64Val[i]);
             break;
         case AtomicType::TYPE_UINT64:
-#ifdef ISPC_IS_LINUX
-            printf("%lu", uint64Val[i]);
-#else
-            printf("%llu", uint64Val[i]);
-#endif
+            printf("%"PRIu64, uint64Val[i]);
             break;
         case AtomicType::TYPE_DOUBLE:
             printf("%f", doubleVal[i]);